1. Field of the Invention
The present invention relates to a mechanical arm, and more particularly to a length-adjustable mechanical arm.
2. Description of the Prior Art
Mechanical arms have been widely used in various fields due to its easy controllability. For example, in mechanical processing field, mechanical arms can be used in combination with machine to pick up work pieces. In medical field, mechanical arms can be controlled by doctor to carry out medical treatment, or in the field of gaming entertainment, mechanical arms can be used to clamp game objects.
As shown in FIG. 1A, a conventional mechanical arm includes a pivotable base 11, a first arm unit 12 pivoted to the base 11, and a second arm unit 13 pivoted to the first arm unit 12. The second arm unit 13 further comprises a pivot 131 pivoted to the first arm unit 12, a rod 132 fixed to the pivot 131, and an accessory 14 mounted on the rod 132. Motion of the accessory 14 is controlled by controlling of the first and second arm units 12, 13.
However, the length of the rod 132 of the second arm unit 13 is fixed and unadjustable, this mechanical arm can only be used for fixed distance operation. Once the operation distance is changed, it has to use another mechanical arm of different length. For example, another mechanical arm rod 152 of the second arm unit 15 as shown in FIG. 1B is longer than the rod 132 of the second arm unit 13 as shown in FIG. 1A is used for longer-distance operation.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages.